Turbine engine and method of cooling

Abstract

A method of mitigating thermal rotor bow in a rotor assembly of a turbine engine may include performing a plurality of motoring cycles. The plurality of motoring cycles may include receiving feedback on a temperature within a turbine engine in a post-shutdown state, actuating a starter motor when the temperature is greater than a predetermined threshold, operating the starter motor for a motoring time to exhaust some residual heat from the turbine engine, and shutting down the starter motor after the motoring time.

What is claimed is: 
     
       1. A method of mitigating thermal rotor bow in a rotor assembly of a turbine engine, the method comprising:
 performing a plurality of motoring cycles, the plurality of motoring cycles comprising: 
 receiving feedback on a temperature within a turbine engine in a post-shutdown state; 
 during the post-shutdown state, initiating actuation of a starter motor when the temperature is greater than a predetermined threshold; 
 operating the starter motor for a motoring time to exhaust some residual heat from the turbine engine; and 
 shutting down the starter motor after the motoring time. 
 
     
     
       2. The method of  claim 1 , wherein the motoring time comprises a predetermined duration. 
     
     
       3. The method of  claim 1 , wherein operating the starter motor for the motoring time comprises operating the starter motor until the temperature is reduced below a second predetermined threshold. 
     
     
       4. The method of  claim 1 , comprising:
 receiving feedback on a running time of the turbine engine; and 
 performing the plurality of motoring cycles if the running time of the turbine engine is greater than a predetermined running time-threshold. 
 
     
     
       5. The method of  claim 1 , wherein actuating the starter motor comprises:
 actuating the starter motor at a preset time after a full stop command corresponding to the post-shutdown state. 
 
     
     
       6. The method of  claim 5 , wherein the preset time permits thermal rotor bow to form before actuating the starter motor. 
     
     
       7. The method of  claim 1 , comprising:
 permitting thermal rotor bow to form when the temperature is less than the predetermined threshold. 
 
     
     
       8. The method of  claim 1 , comprising:
 determining how long to operate the starter motor once actuated to ensure residual heat within the turbine engine is exhausted. 
 
     
     
       9. The method of  claim 8 , comprising:
 determining the motoring time, the motoring time selected to exhaust some residual heat from the turbine engine. 
 
     
     
       10. The method of  claim 9 , comprising:
 determining a predetermined duration; and 
 shutting down the starter motor after the motoring time, wherein the motoring time is less than or equal to the predetermined duration, and wherein the predetermined duration is selected to reduce unnecessary wear to the starter motor. 
 
     
     
       11. A method of mitigating thermal rotor bow in a rotor assembly of a turbine engine, the method comprising:
 receiving feedback on a temperature within a turbine engine in a post-shutdown state; 
 during the post-shutdown state, initiating actuation of a starter motor at a first time when the temperature is greater than a predetermined threshold; 
 operating the starter motor for a first motoring time to exhaust some residual heat from the turbine engine; 
 shutting down the starter motor after the first motoring time; 
 receiving additional feedback on the temperature within the turbine engine in the post-shutdown state after the first motoring time; 
 actuating the starter motor at a second time when the temperature is greater than the predetermined threshold; and 
 operating the starter motor for a second motoring time to exhaust some additional residual heat from the turbine engine; and 
 shutting down the starter motor after the second motoring time. 
 
     
     
       12. A turbine engine comprising:
 a rotor assembly; 
 a starter motor coupled to the rotor assembly; and 
 a control system configured to perform a plurality of motoring cycles configured to mitigate thermal rotor bow in the rotor assembly, respective ones of the plurality of motoring cycles comprising: 
 receiving feedback on a temperature within the turbine engine in a post-shutdown state; and 
 during the post-shutdown state, initiating actuation of the starter motor when the temperature is greater than a predetermined threshold; 
 operating the starter motor for a motoring time to exhaust some residual heat from the turbine engine; and 
 shutting down the starter motor after the motoring time. 
 
     
     
       13. The turbine engine of  claim 12 , wherein the motoring time comprises a predetermined duration. 
     
     
       14. The turbine engine of  claim 12 , wherein operating the starter motor for the motoring time comprises operating the starter motor until the temperature is reduced below a second predetermined threshold. 
     
     
       15. The turbine engine of  claim 12 , wherein actuating the starter motor comprises:
 actuate the starter motor at a preset time after a full stop command corresponding to the post-shutdown state. 
 
     
     
       16. The turbine engine of  claim 15 , wherein the preset time permits thermal rotor bow to form before actuating the starter motor. 
     
     
       17. The turbine engine of  claim 12 , wherein the control system is configured to:
 permit thermal rotor bow to form when the temperature is less than the predetermined threshold. 
 
     
     
       18. The turbine engine of  claim 12 , wherein the control system is configured to:
 determine how long to operate the starter motor once actuated to ensure residual heat within the turbine engine is exhausted. 
 
     
     
       19. The turbine engine of  claim 18 , wherein the control system is configured to:
 determine the motoring time, the motoring time selected to exhaust some residual heat from the turbine engine. 
 
     
     
       20. The turbine engine of  claim 19 , wherein the control system is configured to:
 determine a predetermined duration; and 
 shut down the starter motor after the motoring time, wherein the motoring time is less than or equal to the predetermined duration, and wherein the predetermined duration is selected to reduce unnecessary wear to the starter motor.